Display devices have been extensively applied to various electronic devices such as mobile phones, digital cameras, notebook computers, televisions, and hosts used for vehicles. In order to improve users' visual experience, the industry is continually improving the optical performance of the display devices.
Taking a quantum dot (QD) display as an example, color saturation can be improved by using a quantum dot color enhancement film or a quantum dot color filter. Some quantum dot displays need a collimated light source to excite quantum dots. However, the viewing angle of the full width at half maximum of a light source provided by an existing backlight module is still undesirable, in which the backlight module fails to provide collimated light rays according to needs. In addition, bright spots distributed like an array are formed when using collimated light rays, which causes uneven brightness and should be avoided. Therefore, to provide a collimated light source and avoid uneven brightness is an important subject in the industry.